Guide rail systems are provided for drawers to be either partially or fully opened or closed and typically consist of a bracket for fixing the system to the article of furniture, a fixed rail mounted on the bracket, a pull-out rail attached to the side of the drawer, and preferably an intermediate rail in between the fixed and pull-out rails. The intermediate rail is slidable over the fixed rail and the pull-out rail is slidable over the intermediate rail due to slidable roller housings disposed within the fixed and pull-out rails. Each of the fixed, intermediate and pull-out rails is also normally disposed with pairs of limit stoppers. The distance traveled by the slidable roller housings between each pair of limit stoppers on each rail element typically defines the travel distance of each rail. When the drawer having this typical guide rail system is either pushed in or pulled out, quite a loud noise is inevitably produced due to direct contact between the ends of the slidable roller housings and the limit stoppers.
In order to overcome this problem, an existing drawer sliding guide rail system with noise damping means is disclosed in Malaysian patent application no. PI 20033759. In addition to the above-described typical guide rail system construction, this prior system has a pair of damping means provided on the intermediate rail. This prior damping means consists of an elongate member of resilient material having a first pair of legs connected on one side by a web with a second pair of legs disposed to contact two U-shaped pieces, one of which is attached to the top surface of the fixed rail and the other is attached to the bottom surface of the pull-out rail. The damping means is retained on the intermediate rail by a tab of material punched out of the web of the rail and folded over to lie in the space between the first pair of legs and clamp the web on the resilient elongate member against the web of the rail. The pair of damping means together with the U-shaped pieces determine the distance of travel of the rail elements.
In this prior system, due to the contact of the damping means with the U-shaped pieces, when the drawer is either initially pushed in or pulled out, the limit stoppers of the rail elements do not engage with the ends of the roller housing thus dampening or eliminating noise. Subsequently, when the drawer is either pushed in further or pulled out further so as to be fully closed or fully extended, the second pair of legs of the resilient elongate member contactable with the U-shaped pieces is compressed resulting in the ends of the roller housings directly hitting the limit stoppers.
As the damping means are provided on the intermediate rail for contact with the U-shaped piece on both the fixed and pull-out rails, this prior system provides for an indirect dampening of the resulting noise when the ends of the roller housings hit the limit stoppers. This lack of direct dampening of the force of the roller housing hitting the stopper would inevitably result in unsatisfactory or negligible noise reduction.
Due to the shape and construction of this prior damping means, the contact surface or force-absorbing surface relative to the U-shaped piece consists of a surface of one of the second pair of legs of the resilient elongate member. In other words, the noise dampening of this prior system is dependent on proper contact between relatively small surfaces i.e. a surface of one of the second pair of legs with an upright surface of the U-shaped piece. In practice, this has proven to be an unreliable and ineffective noise dampening method especially, when great or excessive force is used to either push in or pull out the drawer. Also, it has been observed that the shape of this damping means does not facilitate frequent, sustained or vigorous usage over long periods of time as the second pair of legs that provide the noise dampening effect when in contact with the U-shaped piece frequently become bent beyond their resilient limit resulting in either improper contact due to the misshapen legs or at worse breaking of the second pair of legs.
Another prior guide rail system having damping means is disclosed in European patent application with publication no. EP 0 868 866 A2. This prior system has damping means comprising of resilient serpentine or meander shaped buffer protrusions that are integral with and protrude from the longitudinal ends of the slidable roller housing (carriages). The distance of travel of the rail elements is determined by the travel distance of the slidable roller housings between the pairs of limit stoppers. The serpentine-shaped protrusions of the roller housings are contactable with the limit stoppers of the rail elements and as such, function to dampen the noise by preventing direct contact of the roller housing ends with the stoppers. In this prior system, the damping means is integral with the roller housing and is made of plastic material.
Although, this prior system provides for direct dampening of the resulting noise when the ends of the roller housings hit the limit stoppers, the serpentine or meander shape of this damping protrusion dictates that the contact surface or force-absorbing surface consists of only the tip of the protrusion. In other words, the noise dampening of this prior system is dependent on contact with the limit stopper via a small surface i.e. the tip of the protrusion with a side surface of the stopper. Again, this is an ineffective noise dampening method especially, when great or excessive force is used to either push in or pull out the drawer. Also, as above, the shape of this damping protrusion does not facilitate frequent, sustained or vigorous usage over long periods of time as the serpentine or meander shape is likely to be bent beyond its resilient limit resulting in unsatisfactory dampening contact due to the misshapen damping protrusion.
Additionally, having the damping protrusion integral with the roller housing is not desirable or practical as in the event of the protrusion becoming ineffective due to it being misshapen for example, it would be necessary to replace the entire roller housing. Replacing this roller housing requires that the drawer be removed from the article of furniture and disengaged from this rail system and subsequently, for the rail system to be disassembled before replacement can be done.
Also, the design of this prior system necessitates that the roller housing having this integral damping protrusion be made of plastic material. Again, this is impractical as it would mean that the load bearing of this guide rail system is constrained enabling it to bear only a relatively light load. This is an undesirable constraint on the versatility of a guide rail system.
This invention thus aims to alleviate some or all of the problems of the prior art, and to provide a sliding guide rail system having damping means that is easily assembled and manufactured, practical, versatile and allows for vigorous and sustained usage.